一物体从静止开始做匀加速直线运动，在第3 s内通过的位移是3 m，则下列说法正确的是（ ）
A．第3 s内的平均速度是2 m/s
B．物体的加速度是1.2 m/s2
C．前3 s内的位移是6 m
D．3 s末的速度是4 m/s
答案：B
题目分析：由位移公式
，
，代入数据得到
，a="1.2" m/s2 ，B对；第3 s内的平均速度
，A错；前3 s内的位移是
，C错；3 s末的速度是
，D错
点评：本题学生要熟练掌握匀变速直线运动的规律、公式，并能进行灵活运用。
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| An old tiger lives in the forest. He seldom (很少) goes to look for food himself. He orders (命令)other animals to _1_ him something to eat. One day he sees a monkey and says, " I'm __2_ , Monkey. Go to the village and bring me a fat pig." "Oh, Tiger," says the monkey. " I __3_ do that. There 4 _ another tiger over there. He also wants a fat pig. He will not let me do anything __5_  you. I am afraid of him." "What?" cries the tiger. "Show _6_ that tiger. I will talk to him." "Come _7_ me, then." Says the monkey. The monkey and the tiger get to a bridge above the river. "Now look down _8 the river." Says the monkey. "Do you 9 the head, the white teeth and large green eyes of a tiger?" "Yes, I do," cries the old tiger. "I will eat him up." With these words the tiger 10_ the river.
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